RE: FM or PCM??
PCM has another advantage. It covers up any minor transmission errors. If you have a minor glitch on the take off or landing( where glitches are likely) The PCM system will not respond. If you are being judged on your flying quality you would get downgraded for this if you used PPM. If you are serious about your flying you cannot give this advantage to your competition.
In the begining every PPM system came with a failsafe system. It was deemed to be unnessesary and dropped. In fact one of the manufactors, PCS, told me that it caused more crashes than it saved.
Today its more a safety factor consideration in that it can be used to shut down the motor in case of transmission failure.